H. BLOTEVOGEL, Hans; SCHULZE, Kati. One or Two or Three? On the Constitution of Potential Metropolitan Regions on Rhine and Ruhr. Raumforschung und Raumordnung | Spatial Research and Planning, DE, v. 68, n. 4, p. 255–270, 2010. DOI: 10.1007/s13147-010-0040-8. Disponível em: https://rur.oekom.de/index.php/rur/article/view/890. Acesso em: 21 sep. 2026.